Prof.S.Sathishkumar - Vidyarthiplus

Prof.S.Sathishkumar www.Vidyarthiplus.com www.kssathishkumar.blogspot.com

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ANNA UNIVERSITY, CHENNAI-25

DEPARTMENT OF MECHANICAL ENGINEERING

QUESTION BANK WITH ANSWERS

2013 Regulation & 2017 Regulation

Subject Code : ME 6004

Subject Name : Unconventional Machining Process

Year/Semester : III/VI

Author

Prof.S.Sathishkumar. BE (Mechanical Engineering)., ME (Engineering Design).,(MBA)

Operations Management.,MISTE

Assistant Professor, Department of Mechanical Engineering

Vel Tech (Owned By RS Trust) Engineering College, Avadi, Chennai-62

Email : [email protected] & [email protected]

Mobile : 9994274071, 9597178818

Face Book : K.s. Sathishkumar

Twitter : K.s. Sathishkumar

mailto:[email protected]

mailto:[email protected]


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SYLLABUS

ME6004 UNCONVENTIONAL MACHINING PROCESSES L T P C 3 0 0 3

OBJECTIVS:

To learn about various unconventional machining processes, the various process parameters and

their influence on performance and their applications

UNIT I INTRODUCTION

Unconventional machining Process – Need – classification – Brief overview.

UNIT II MECHANICAL ENERGY BASED PROCESSES

Abrasive Jet Machining – Water Jet Machining – Abrasive Water Jet Machining - Ultrasonic

Machining.(AJM, WJM, AWJM and USM). Working Principles – equipment used – Process

parameters – MRR- Applications.

UNIT III ELECTRICAL ENERGY BASED PROCESSES

Electric Discharge Machining (EDM)- working Principle-equipments-Process Parameters-Surface

Finish and MRR- electrode / Tool – Power and control Circuits-Tool Wear – Dielectric – Flushing

– Wire cut EDM – Applications.

UNIT IV CHEMICAL AND ELECTRO-CHEMICAL ENERGY BASED PROCESSES

Chemical machining and Electro-Chemical machining (CHM and ECM)-Etchants – Maskant -

techniques of applying maskants - Process Parameters – Surface finish and MRR-Applications.

Principles of ECM- equipments-Surface Roughness and MRR Electrical circuit-Process

Parameters- ECG and ECH - Applications.

UNIT V THERMAL ENERGY BASED PROCESSES

Laser Beam machining and drilling (LBM), plasma Arc machining (PAM) and Electron

Beam

Machining (EBM). Principles – Equipment –Types - Beam control techniques – Applications.

OUTCOMES:

Upon completion of this course, the students can able to demonstrate different unconventional

machining processes and know the influence of difference process parameters on the performance

and their applications.


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UNIT – I: INTRODUCTION

PART - A (2 Marks)

1. What do you mean by Unconventional machining process?

Unconventional machining process is defined as a group of processes that remove excess

material by various techniques involving mechanical, thermal, electrical or chemical

energy or combinations of these energies but do not use a sharp cutting tools as in

traditional manufacturing processes.

2. List down various mechanical energy based Unconventional machining processes.?

The various mechanical processes that are mechanical energy based are

1. Abrasive Jet Machining (AJM)

2. Ultrasonic Machining(USM)

3. Water Jet Machining(WJM)

4. Abrasive Water Jet Machining(AWJM)

3. How will you compare various non-traditional processes?

The comparison of various non-conventional machining process can be done

based on the following parameters.

5. Physical parameters involved in the processes

6. Capability of machining different shapes of work material

7. Applicability of different processes to various types of material

8. Operational characteristics of manufacturing

9. Economics involved in the various processes.


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4. What are the different machining characteristics with respect to which the nontraditional

machining processes can be analyzed?

The machining characteristics of different non-conventional processes can be analyzed

with respect to

1 Metal removal rate

2 Tolerance maintained

3 Surface finish obtained

4 Depth of surface damage

5 Power required for machining

5. What are the various thermal energy methods of UCM?

The various thermal energy methods of UCM are Laser Beam machining Plasma Arc is

machining, Electron beam machining and Ion Beam machining.

6. What are the various chemical energy methods of UCM?

The various chemical energy methods of UCM are Electro chemical machining, Electro chemical

grinding, Electro chemical honing and Electro chemical discharge machining.

7. What are the various mechanical energy methods of UCM?

The various mechanical energy methods of UCM are ultrasonic machining, abrasive jet

machining and water jet machining.

8. What is the unconventional process which is used to remove maximum material?

The processes which remove maximum material are Electro chemical machining and plasma arc

machining.

9. What is the unconventional process which removes minimum material?

The processes which remove minimum material are Electron beam machining.

10. What is the unconventional process which consumes maximum power?

The process which consumes maximum power is laser beam machining.


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11. What is the unconventional process which consumes minimum power?

The process which consumes minimum power is plasma arc machining.

12. What type of energy source is applied in the ion beam machining process?

Ionized substance is used as energy source in ion beam machining process.

13. What type of energy source is applied in ECM process?

Electrical current is used as energy source in ECM process.

14. What is type of energy source applied in chemical machining process?

Corrosive agents are used as energy source in chemical machining process.

PART – B (16 Marks)

1. Write down the energy transfer media, energy source and mechanism of metal removal for the

nontraditional machining processes.(16 marks)

2. Explain the classification of Unconventional machining according to major energy source

employed?(8marks)

3. What are the various aspects to be considered while selecting a UCM process?

4. How to classified Unconventional machining process? (8marks)

5. Classify unconventional machining processes based on basic mechanism involved in the

process, sources of energy required for material removal, medium of transfer of energies and type

of energy required to shape the materials.(16 marks)

6. What do you understand by the word ‘unconventional’ in unconventional machining process?

Is it justified to use this word in the context of utilization of these processes in the shop

floor? (8 marks)

7. What is the need for development of unconventional machining processes? Explain with

examples.(16 marks)

8. What is the importance of unconventional machining?(8 marks)

9. Compare the process capabilities and limitations of electrical energy based and mechanical energy

based unconventional processes. (16 marks)


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UNIT – II: MECHANICAL ENERGY BASED PROCESSES

PART – A (2Marks)

1. What are the desirable properties of carrier gas in AJM?

The desirable properties of carrier gas in AJM are

1. It should be cheap and easily available.

2. It should benon-toxic.

3. It should dry quickly.

4. Generally used carrier gases are: Air, N2, CO2, He, etc.,

2. What are the Process parameters affecting the MRR in AJM?

The Process parameters affecting the MRR in AJM are

Gas pressure.

Velocity of particles.

Abrasive mass flow rate.

Mixing ratio.

Nozzle tip distance (SOD)

3. What are the various applications of AJM?

The applications of AJM are

5. For abrading and frosting glass, it is more economical than acid etching and grinding.

6. For doing hard suffuses safe removal of smears and ceramics oxides on metals.

7. Resistive coating etc from ports to delicate to withstand normal scrapping.

8. Delicate cleaning such as removal of smudges from antique documents.

9. Machining semiconductors such as germaniumetc.

4. List down any four variables in AJM that influence the MRR?

The four variables in AJM that influence the material removal rate are

Gas Pressure.

Velocity of Particles.

Abrasive mass flow rate.

Mixing ratio.


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5. What are the characteristics of carrier fluid?

The characteristics of carrier fluid are

1. good wetting characteristic

2. High thermal conductivity

3. Non-toxic and non-corrosive.

4. Should have low viscosity.

6. What are the types of feed mechanisms used in USM?

The types of feed mechanisms used in USM are

Spring type

Counter – weight type

Motor type

Pneumatic and hydraulic type

7. What are the various abrasives used in AJM process?

The various abrasives used in AJM process are

Aluminum oxides

Silicon carbides

Crushed glass

Sodium bicarbonate

Dolomite

8. What is the need for transducer in USM?

The need for transducer in USM is used for converting electrical energy into mechanical

energy in the form of high frequency vibration.Magnetostriction transducer and piezoelectric

transducer is types of transducers are used in ultrasonic machining processes

9. State the working principle of USM.

USM is a mechanical material removal process in which the material is removed by repetitive

impact of abrasive particles carried in liquid medium on to the work surface, by a shaped tool,

vibrating at ultrasonic frequency


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10. Write the typical applications of Ultrasonic machining

The typical applications of Ultrasonic machining are

Almost all the material can be machined except some soft materials.

Diamond, Tungsten, Tungsten carbide, and synthetic ruby can be successfully machined.

USM can be used for drilling, grinding, profiling, coining, threading and even for welding.

For preparing wire drawing dies and tool room items.

Used in jewellery for shaping jewels

Drilling of screw threads and curved holes in brittle materials.

11. What is ultrasonic transducer?

The device used for converting any type of energy into ultrasonic wavers or

vibration is called ultrasonic transducer.

12. What is ultrasonic machining?

USM is a mechanical material removal process in which the material is removed

by repetitive impact of abrasive particles carried in liquid medium on to the work

surface, by a shaped tool, Vibrating at ultrasonic frequency.

13. What is magnetostrictive effect?

It is the one in which the material changes its dimension is in response to a magnetic field.

14. What is the purpose of concentrator used in USM?

The main purpose of the concentrator is to increase the amplitude of the vibration

obtained from the transducer.

15. What is abrasive Slurry?

The abrasive slurry is nothing but a mixture of abrasive grains and the carrier fluid, generally

water.

16. What are the abrasives used in AJM process?

Aluminum oxide, silicon carbide, glass powder, dolomite.


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17. What is the carrier gases used in AJM process?

Nitrogen, carbon dioxide, helium and compressed air

18. What is the tool materials used in USM?

Low carbon steels and stainless steels.

18. What is piezoelectric effect?

When mechanical force is applied to one pair of opposite faces of certain crystals

like quartz, tourmaline etc., equal and opposite electrical charges appear across its

other faces.

19. What are the disadvantages of WJM process?

The disadvantages of WJM process are

1. High initial cost

2. Difficult to machine hard materials.


1. Describe the principle and equipment for AJM. Explain the process parameters which control

the AJM machining quality.

2. Explain the working principle and equipment’s of Ultra Sonic Machining with neat sketch.

Mention its applications, advantages and limitations.

3. Explain the applications, advantages and limitations of WJM?

4. Compare the USM, WJM and AJM in terms of process capabilities and limitations.

5. Discuss the process parameters in WJM process.(8 marks)

6. Explain the process capabilities of WJM with examples.(8 marks)

7. Explain the following in detail.

a) Types of transducers for USM.

b) Feed mechanism in USM.

c) USM typical applications


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d) Abrasives for USM.(16 marks)

8. Briefly explain the effect of operating parameters on material removal rate. List the

applications of USM.(8 marks)

9. Discuss the effects of the following parameters on the MRR and surface finish inUSM.

e) Amplitude and frequency.

f) Abrasive size.

g) Concentration of abrasives.

h) Material hardness.(16 marks)

10. Describe the principle and equipment for WJM. Explain the different applications and process

control features of WJM.

UNIT – III: ELECTRICAL ENERGY BASED PROCESSES

PART – A (2 Marks)

1. Define – Electrical discharge machining

EDM is the controlled erosion of electrically conductive materials by the initiation of rapid and

repetitive spark discharge between the electrode tool to the cathode and work to anode separated

by a small gap kept in the path of dielectric medium. This process also called spark erosion.

2. What is the purpose of dielectric in EDM?

The various purposes of dielectric in EDM are

It acts as an insulating medium

It cools the spark region and helps in keeping the tool and work piece cool.

It maintains a constant resistance across the gap.

It carries away the eroded metal particles.

3. List down the various applications of EDM?

The various applications of EDM are

Hardened steel dies, stamping tools, wire drawing and extrusion dies, header dies, forging dies,

intricate mould cavities and such parts are made by the EDM process.


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The process is widely used for machining of exotic materials that are used in aerospace and

automatic industries.

EDM being a non-contact type of machining process, it is very well suited for making fragile

parts which cannot take the stress of machining. The parts that fit such profiles include washing

machine agitators; electronic components, printer parts and difficult to machine features such as the

honeycomb shapes.

Deepcavities, slotsandribscanbeeasilymadebyEDMasthecuttingforcesareless and longer

electrodes can be used to make such collets, jet engine blade slots, mould cooling slots etc.

Micro-EDM process can successfully produce micro-pins, micro-nozzles and micro-

cavities.

4. What are the properties required for dielectric fluid for EDM?

The various properties required for dielectric fluid for EDM are

Stable Dielectric strength

It should have optimum viscosity

It should have high flashpoint

It should be chemically stable at high temperature and neutral,

It should not emit toxic vapours

5. List down the advantages of EDM.

The advantages of EDM are

Any materials that are electrically conductive can be machined by EDM.

Materials, regardless of their hardness,strength,toughness and microstructure can be easy

machined / cut by EDM process

The tool (electrode) and work piece are free from cutting forces

Edge machining and sharp corners are possible in EDM process

Thetoolmakingiseasierasitcanbemadefromsofterandeasilyformablematerialslikecopper,

brass and graphite.

The process produces good surface finish, accuracy and repeatability.

6. What is the function of servo control system in EDM?

EDM requires that a constant arc gap be maintained between the electrode and the work piece

to obtain maximum machining efficiency. Therefore EDM tool in corporate some form of servo


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control.

7. What are the material that can be machined in EDM? (N/D-2006)

The various materials that can be machined in EDM are

Copper, brass, alloys of Zinc tin.

Hardened plain carbon steel

Copper tungsten, silver tungsten, tungsten

Copper graphite and graphite.

8. What do you mean by recast layer with reference to the EDM?

Metal heated to a temperature above the melting point and which is not displaced by

the action of the spark discharge resoldifies as recast metal.

9. Mention a few varieties of power supply circuits commonly used in EDM.

R-Circuit.

Rotary impulse generator.

Controlled pulse (vacuum tube).

Oscillator controlled pulse.

Transistor pulsed circuit.

10. What are the prime requirements of tool material in EDM?

The prime requirements of tool material in EDM are

1. It should be electrically conductive.

2. It should have good machinability.

3. It should have low erosion rate.

4. It should have low electrical resistance.

11. What is the dielectric fluids commonly used in EDM?

Petroleum based hydro carbon fluids.

Paraffin, white sprite, transformer oil.

Kerosene, mineral oil.

Ethylene glycol and water miscible compounds.


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12. Define–Re hardening

While metal heated to a temperature above the critical and then rapidly cooled by the

flowing dielectric fluid the metal is re hardened.

13. Define –Wear Ratio

Wear ratio=Work piece material removed/Loss of electrode material.

14.List down the process parameters which govern the MRR in EDM?

The various process parameters which govern the MRR in EDM are

1. Energy discharge

2. Capacitance

3. Size of work piece

4. M/c tool design

15. What is the effect of capacitance in EDM? ?

Increasing the capacitance causes the discharge to increase and increase both the peak current and

discharge time.

16. What is overcutting in EDM process?

Overcutting is the cutting of larger cavity than the size of electrode in EDM process.

17. What are the applications of wire cut EDM?

It is best suited for the production of gears, tools, dies, rotors, turbine blades and cams.

18. What are the materials that cannot be used for machining in EDM?

Non conducting materials

19. What is the shape of electrode in travelling wire EDM process?

A very thin wire made of brass or molybdenum with circular cross section is generally used.

20. What is the wear ratio for non metallic electrodes?

It varies from 5:1 to50:1


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1. Explain the EDM process and list its advantages, disadvantages and applications.

2. Explain the Wire cut EDM and list its advantages, disadvantages and applications.

3. Explain the process parameters which govern the EDM/ Wire EDM process.

4. Explain different types of control circuits used in EDM.(8marks)

5. Write about various types of flushing techniques used in EDM.(8marks)

6. State the recent developments in EDM and Wire cut EDM.(8 marks)

7. How will you carry out the analysis for optimization of metal removal rate in EDM process?

8.What are the steps that are to be adopted in sequence while applying the linear programming

technique to optimize the metal removal rate in EDM?

9. Explainhowthestratifiedwireworks.Also discuss about the recent developments in wire EDM.

(8 marks)

10. Explain the classification and characteristics of various spark erosionenerators.


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UNIT – IV : CHEMICAL AND ELECTRO CHEMICAL ENERGY BASED

PROCESSES


1. What are the materials used to make the tool electrode in ECM?

Copper and copper alloys, titanium, aluminum, brass, bronze, carbon, Monel and

reinforced plastic.

2. What are the main functions of electrolysis in the ECM?(M/J-2006 &N/D-2006)

The main function of electrolysis in ECM is to complete the electric circuit between

the tool and the work piece and to allow the reaction to proceed efficiently. Apart

from this the other functions are:-

To remove the products of machining from the cutting region.

To carry away the heat generated during the chemical reaction.

To avoid ion concentration at the work piece- tool gap.

3. What are the properties that are expected from the electrolysis used in the ECM?

The properties that are expected from the electrolysis used in ECM are

High thermal conductivity.

Low viscosity and high specific heat.

Should chemically stable even at high temperature.

Should be non-toxic and non-corrosive.

4. What are the electrolytes commonly used in ECM?

The electrolytes commonly used in ECM are15 -20 % Nacl in water, sodium nitrate,

Potassium nitrate, sodium sulphate, sodium chromate and potassium chloride.

5. What are the results of improper selection of electrolyte in ECM?

The results of improper selection of electrolyte in ECM are

1. Low machining rate.

2. Over cut and stray cutting.


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6. What are the advantages of ECM?

The advantages of ECM are

1. ECM is simple, fast and versatile method.

2. Surface finish can be extremely good.

3. Fairly good tolerance can be obtained.

7. What are the limitations of ECM?

The limitations of ECM are

4. Large power consumption and the related problems.

5. Sharp internal corners cannot be answered.

3. Maintenances of higher tolerances require complicated contours.

8. How the current density affects the MRR?

Currentdensityiscontrollednotonlybytheamountofcurrentbutalsobythesizeofthe gap between the

tool and the work piece. A small gap results in high current density, which in turn produces

more material removal.

9. What are the applications of ECM?

ECM is used for sinking, profiling and contouring, multi hole drilling, trepanning, broaching,

honing, steel mill applications, surfacing, sawing, contour machining of hand to hand machine

materials.

10. What are the important functions of abrasive particles used in ECG?

Itactsasinsulatortomaintainasmallgapbetweenthewheelandworkpiece.Theyare electrolysis products

from the working area. To cut chips if the wheel should contact the work piece particularly in the

event of power failure.

11. Write the Faraday’s first law of electrolysis.

The amount of any material dissolved or deposited is proportional to the quantity of

electrolyte passed.


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12. Write the Faraday’s second law of electrolysis.

The amount of different substances dissolved or deposited by the same quantity

of electricity are proportional to their chemical equivalent weight.

13. Write the Ohm’slaw.

Current, I = V/R

V = Voltage

R = resistance

14. What are the factors that influence oxidation in ECM?

The various factors that influence oxidation in ECM are

Nature of work piece.

Type of electrolyte.

Current density.

Temperature of the electrolyte.

15. What are the materials used to make the tool electrode in ECM?

Copper and copper alloys, titanium, aluminum, brass, bronze, carbon, Monel and reinforced plastic.

16. What are the maskants used in CHM?

Butyl rubber, neoprene rubber, polymers and polyethylene.

17. What are the etchants used in CHM?

Caustic soda, hydrochloric acid, nitric acid and iron chloride.

18.What are the process parameters of ECM?

Current density, tool feed rate, type of electrolyte

19. What are the limitations of ECM?

Sharp internal corners cannot be obtained and Post machining cleaning is needed.

20. What are the disadvantages of ECG?

High initial cost, High power consumption and less MRR.


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1. Describe the process of electro chemical machining.(8marks)

2. Describe the chemistry involved in ECM process.

3. Discuss about the economics of ECM.(8 marks)

4. List out the advantage of EGC over conventional grinding.(8 marks)

5. Mention the product application of ECG.(8 marks)

6. Discuss about the electrochemical honing and electro chemical grinding

7. Explain the principle of working, equipment’s, Applications, Advantages and drawbacks of

chemical machining.(16 marks)

8. Explain the principle of working, equipment’s, Applications, Advantages and draw Backs of

electrochemical machining.

9. Explain the principle of working, equipment’s and Applications of Electro Chemical Grinding.

10. Briefly discuss about the effect of high temp and pressure of electrolyte on the ECM process.

11. Describe the working principle and elements of chemical machining. What are the factors on

which the selection of a resist for use in chemical machining?

12. Whatarethespecificadvantagesofusingchemicalmachiningoverelectrochemicalmachining?

Give some of the practical applications of chemical machining process

13. Explain in detail the ECM process with neat sketch and also mention the advantages and

applications.


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UNIT – V: THERMAL ENERGY BASED PROCESSES


1. What are the limitations of EBM?

The various limitations of EBM are

The primary limitations are the high capital cost of the equipment and necessary regular

maintenance applicable for any equipment using vacuum system. Moreover in EBM there

is significant amount of non-productive pump down period for attaining desired vacuum.

Though heat affected zone is rather less in EBM but recast layer formation cannot be

avoided.

Skilled operator is required for operation.

Limited to 10mm material thickness.

2. What is transferable and non-transferable arc in Plasma Arc Machining?

Transferable arc Non-transferable arc

The work piece is directly connected

to the positive terminal.

The positive terminal connected to

the nozzle instead of work

piece.

Used for conductive materials Used for non conductive materials

3. What is the acronym of LASER?

The acronym of LASER is Light Amplification by Stimulated Emission of Radiation

4. List any two gases used in PAM?

The two gases used in PAM are

1. Hydrogen

2. Nitrogen

3. Argon

5. Why is the deflection coil provided for electron beam machining?

The functions of the deflection coil us to direct and focus the electron beam to the

machining zone.


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6. What is the purpose of vacuum chamber in EBM?

The purpose of vacuum chamber in EBM is

4. To avoid the collision of electron beam with air molecules.

5. To avoid the oxidization of electron gun due to the presence of oxygen and high

temperature.

7. Define - Electron Beam?

The electrons emitted from the electron gun (cathode) traveled at a high velocity

towards anode. This is called electron beam.

8. State the characteristics of laser beam?

The characteristics of laser beam are

High intensity

Mono chromatic

Highly Coherent

9. List the process parameters of PAM?

The process parameters of PAM are

Properties of Gas used

Material to be cut

Standoff distance

10. Contrast LBM and EBM?

LBM EBM

Material is removed by high

intensity

LASER beam

Material removal is done by

high

velocity of electrons

Limited for only thin materials Used for micro drilling, narrow slots


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11.Describe commonly used gas mixture in PAM and their corresponding work materials?

Gas mixture

Material

N2-H2/ Argon-H2 Stainless steel and non-ferrous metals

N2-H2, compressed air Carbon and alloy steels, Cast iron

12. What is the function of water muffler in PAM?

The function of water muffler is to cool the nozzle and electrode of PAM.

13. What is the principle of PAM?

In PAM the high temperature plasma (ionized gas) melts and blasts away the work material.

14. Why deflection coil is provided for EBM?

It is used to deflect the electron beam to different spots on the work piece.

15. What is plasma?

When a flowing gas is heated to a sufficiently high temperature, it becomes partially

ionized and it is known as plasma

16. What are the two methods of focusing the electron beam?

Electromagnetic focusing and Electro static focusing

17. What are the disadvantages of PAM?

High cost of equipment and the metallurgical changes.

18. What are the types of plasma arc torches?

Direct arc plasma torches and indirect arc plasma torches.

19. What materials can be machined by using laser beam?

All materials except those having high thermal conductivity and high reflectivity.


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1. Why is Electron Beam Machining carried out in vacuum? Explain the process with neat

sketch.

2. Describe PAM process with neat sketch and write about its process parameters, advantage

and applications.

3. Draw the schematic set-up of PAM. Indicate various parts.

4. Explain the process of LBM and PAM with a neat sketch.

5. Discuss the process parameters of EBM and their influence on machining quality.

6. Explain the process capabilities of EBM and PAM.(8marks)

7. List out the advantage and limitation of LBM process.(8marks)

8. List out the advantage and limitation ofPAMprocess.8marks)

9. Mention the application of EBM.(8 marks)

10. Explain the principles and elements of EBM, also how the work table is protected from

Getting damaged by electron beam.

11. Describe Discuss how the process variables influence MRR, HAZ and pattern generation.

12. What are the specific advantages of using chemical machining goverelectrochemical

machining? Give some of the practical applications of chemical machining process


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Happy Learning My Dear Sweet Hearts

**********All the Best*************

By: Author

Prof.S.Sathishkumar - Vidyarthiplus

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